1. Field of the Invention
The present invention relates to testing of the pressure and abrasion sensitivity of granular materials; to this end several testing methods are known. For instance, dumping sensitivity tests have been developed in numerous modifications; however, the numerical values obtained in these tests can, in general, not be compared to each other (cf. v. Bogdandy, Engell: Die Reduktion der Eisenerze (Reduction of Iron Ores), 1967, edited by Verlag Stahleisen, pp. 400 et seq.).
2. Description of the Prior Art
In most cases, abrasion sensitivity is tested in drums; the percentage of a certain range of grain-size fractions, e.g. 0 to 0.5 mm, after the drum process is considered as the test value in these tests.
A method of this type, wherein the granular material is exposed to mechanical stress and wherein either the variation of the weight proportions of individual grain-size fractions due to this stress in comparison to the corresponding initial values of a representative sample, by way of screening analysis, or the variation of the permeability to gas of the processed sample in comparison to that of the non-processed sample is applied as a standard of pressure sensitivity and abrasion sensitivity, is known from German patent application No. 17,73,737 published for opposition.
The disclosure of German published patent application P 17,73,737 is incorporated herein by reference.
In the aforementioned methods, however, the test materials are tested only in the form of a loose bulk material whose grains still have a comparatively high freedom of relative movement during the test procedure. Hence, the results of such test procedures are practically irrelevant for a majority of industrial processing engineering, i.e. for those fields where grain lots in dense packing (i.e. with an intense mutual influence of the individual grains) plays a decisive role.